1. Field of the Invention
The present invention generally relates to a positioning system. More specifically, the present invention relates to a positioning system, a terminal device, a positioning device, a control method for a terminal device, a control program for a terminal device, and a computer-readable recording medium for recording a control program for a terminal device for positioning a current position based on position related-signals from position information satellites.
2. Background Information
Conventionally, positioning systems for positioning the current position of a SPS receiver utilizing an SPS(Satellite Positioning System), for example, as a satellite navigation system have been put into practical use. Such positioning systems include a system for transmitting correlation result information that the SPS receiver has obtained by receiving signals from the SPS satellites to an external positioning server and allowing the positioning server to perform positioning of the current position of the SPS receiver (hereinafter, referred to as “server positioning system”). (Such a system is shown in Japanese Patent Application Publication No. 2000-131415, especially FIG. 1 etc. Japanese Patent Application Publication No. 2000-131415 is hereby incorporated by reference. Here, the correlation result information is information necessary for the positioning server to perform positioning computation of the current position of the SPS receiver, for example, carrier phase, code phase, Doppler frequency. This server positioning system is advantageous in that the processing load on the SPS receiver can be reduced because there is no need for the SPS receiver itself to perform positioning computation.
However, in the above described related technology, it is necessary to transmit the correlation result information of the positioning server for positioning the current position of the SPS receiver. This means that a large volume of data communication is generated in a service utilizing an application such as pedestrian navigation that requires one positioning per several seconds (s), for example. When the volume of data communication is large, there is a problem in that a communication charge increases for a service user.
Further, in the case where the above described service is provided to a large number of users, when volumes of independent data communication are large, equipment such as a server for handling the volumes is required and that brings significant disadvantages to service providers.
In view of the above, it will be apparent to those skilled in the art from this disclosure that there exists a need for an improved a positioning system, a terminal device, a positioning device, a control method for terminal device, a control program for terminal device, and a computer-readable recording medium for recording a control program for terminal device for positioning a current position based on position related-signals from position information satellites. This invention addresses this need in the art as well as other needs, which will become apparent to those skilled in the art from this disclosure.